Invented by Otto Bayer in 1937, Polyurethane (PUR) foam is an extremely common material, especially in our cars (bumpers, dashboards, seats, etc.) and in our homes (as insulating material for walls, pipes and refrigerators). PUR is produced by mixing alcohol and isocyanates. The resulting reaction generates gas bubbles which become trapped in the curing compound.

Pre-formed foam plastics are produced by casting processes, where the reactants are mixed just before they enter the mould. When foaming large structures, the curing process may start while the reactants are still being fed into the form, which can result in poor product quality with undesirable voids. To ensure successful filling, both the filling and foaming processes must therefore be optimized together.